Method and device for wireless control of master clocks



V. PFEFFER Oct. 21, 1952 METHOD AND DEVICE FOR WIRELESS CONTROL OF MASTER CLOCKS Filed Sept. 5, 1946 s Sheets-Sheet)- I N VEN TOR.

V. mm r Oct. 21, 1952 v, p 2,614,383

METHOD AND DEVICE FOR- WIRELESS CONTROL QF MASTER CLOCKS Filed Sept. 5, 1946 'zisfiee'ts-sneet 2 F/E.Z

IN VEN TOR.

l Ffe/ er Oct. 21, 1952 v, PFEFFER 2,614,383

METHOD AND DEVICE FOR WIRELESS CONTROL MASTER CLOCKS Filed Sept. 5, 1946 3 Sheets-Sheet 3 IIIT'I Patented Oct. 21, 1952 METHOD AND DEVICE FOR WIRELESS CONTROL OF MASTER CLOCKS Vaclav Pfeffer, Zelena, Prague, Czechoslovakia Application September 3, 1946, Serial No. 694,665 In Czechoslovakia September 27, 1945 2 Claims.

' is thus formed, giving the same time indication within the range of a master-clock. A masterclock, even if constructed with the utmost care andat great expense, is however not free from deviations, which are even increased by the master-clock being burdened by the controlling emitters of electric impulses to subsidiary clocks;

a time difference or deviation from the correct time in a particular clock-system is the inevitable result, which is further increased by the sum of deviations multiplied by their double characteristic, i. e. in one case a positive and in the other a negative deviation. Considering the present state of art in this respect, it is, there'fore,possibie to speak of time synchronization only locally. In order to remove these drawbacks, and to extend the synchronization of time, clocks controlled by impulses, emitted by wireless have already been devised. Such a device requires a continuous operation of the emitter and receiver and is extremely uneconomic, because of its continuous consumption of electric current and excessive wear of components. Its practical application fails owing to dependence on special emitting stations.

In another design the time synchronization is achieved so that at certain intervals, for instance, one hour intervals, the time deviation of the clockwork is eliminated by omitting a particular wireless impulse characterized by a certain tonal frequency and a predetermined duration. Even this method, which requires a complete separation from the usual broadcast- I ing, does not fulfill the object in view, as even with a perfect selectivity of the filtering means i in the output circuit, there remain indispensable tolerances and the strictly limited field detects also tones of both neighbouring frequencies and all harmonic frequencies.

The other supposed safeguard is insufficient with respect to its one-sided limitation of the minimum length of time, leaving open the possibility of an incorrect regulation by any incidental impulse, which has reached or exceeded the predetermined limit, such as for instance an impulse formed by cumulative effect of atmospheric disturbances. The lack of reliability is the more serious, if a master-clock is concerned, in which case the influence of an undesirable impulse extends to the entire clock-system so that rectification by the next correct impulse is no longer possible.

According to the invention any foreign influence is reliably eliminated irrespective of whether itv occurs by accumulation of atmospheric disturbances or incidental adjacent impulses, the regulation of the master-clock being independent of the emission of a special control-impulse or silence of the emitter. According to the invention the intermittent or 00- casional control of the master-clock is performed byv a system of wireless emitted impulses of a difierent order and duration. So for instance, the respective member may be adjusted to respond to a suitable time signal. In a practical embodiment, described below, the device according to the invention is adjusted to a time signal, consisting of four short and one longer impulse, with interposed short intervals. The particular impulses which compose such a signal, are detected in every detail or in groups or in their total by the analyzer of the clock; the end of the last impulse of the signal combination, as measured by a pre-adjusted controlmember or controller, must coincide with the control member for the sum or total. As the analyser pre-supposes an exact fulfilment of conditions to which it is set, i. e. not only the length and sequence of the assumed impulses, but also the length and sequence of the various intervals, it returns automatically into its initial position, if any one of such conditions is not fulfilled. The transmission of current to the proper control member then does not take place.

By means of the device according to the invention an absolutely reliable remote control of the master clock is achieved and thus it has been possible for the first time to obtain a universal synchronized time indication.

As a source of power for the drive of the master-clock, a spring member is provided with means which allows the winding and unwinding of the spring within the limits of its constantelasticity, preventing at the same time its overwinding. The said member is continuously brought to its fully wound position by means of a suitable gearing from a Ferraris motor and in this way accumulates power in case the electric current supply be temporarily out off. The spring member drives by means of a gearing on the one hand a clock-work, which'through a suitable gearing, provided with a sliding clutch imparts rotation to a correcting initiator mechanism and on the other hand, to an emitter of impulses serving forth e drive of subsidiary clocks, said emitter being arranged in such a way, that in addition to normal minute-impulses of alternate polarity, it emits also special correction impulses, the current-flow of which corresponds to the polarity of the preceding normal impulse. The velocity of rotation of the said device is suitably adjusted to its purpose and may be controlled by the braking influence of eddy currents. The correcting initiator mechanism co-operates with a control member, which is operated by the above analyser at the time of reception of the expectedsignal, for instance once in 24 hours, to compensate for the positive or negative time-deviation by advancing the mechanism returning or arresting it, irrespective of the operation of the -clock-work.

The wireless receiver of the clock, the output circuit of which is tuned to the tonal frequency 'of the control-signal or provided with a frequen'cy relay, operates for a short time, for instance four minutes, beginning at about 2 minutes before the desired remote control of the clock. The receiver is operated by an associated subsidiary clock, the adjustable switching operation of which has further the purpose of a control clock.

An example of a preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which:

Fig. '1 represents an overall diagram of the master-clock,

Fig. 2 a simplified modification of the analyzer,

Fig. 3 a detail of the releasing mechanism Fig. 4 a wiring diagram of a frequency relay, which may be used if desired, and

Figs. 5 and 6 a modified simple embodiment of the control-mechanism, in plan view and side view respectively.

The master-clock consists of a receiving unit, a subsidiary clock modified for switching purposes, an analyzer of the impulse combinations and a specially arranged clock-work.

The clock-work consists of a Ferraris motor,

- operatively connected through a suitable gearing with a spring member 2, which is provided with a known device 3 preventing an overwinding of the spring. As a safeguard against unwinding of the tension spring there is provided a suitably located ratchet wheel 4, co-operating with a spring-loaded pawl 5. The springmember imparts rotation to a gear 5, with which a gearing system engages which drives the clock-work itself and which at the end of the stepped-up gearing is subjected to the escapement 1. The rate of operation of this mechanism determines the velocity of rotation of a related gear 8, which is connected by means of a slipping clutch I03 with a correcting initiatormechanism composed of two rigidly connected discs 9 and I0 and provided with alternately offset cam slots or notches on their circumferences.

The pitch of the notches is regular, so that the notches in the disc 9 are offset through half a pitch with regard to the notches in the disc III. The total number of notches in both discsis an even number which is the result of sixty divided by the number of revolutions of the correcting initiator mechanism in one hour. In the given example there are altogether six notches and by the selected ratio of the gearing the correcting initiator mechanism is rotated ten times in an hour. Pawls II and I2 are arranged for cooperation with the notches, said pawls bein adapted to abut at their extended ends against alternating pins in a two-arm lever I3, in such a way that a pin projecting in one direction abuts against the pawl l I, whereas a pin projecting in the other direction abuts against the pawl 12.

In order to prevent manufacturing inaccuracies of the pawls from influencing the accuracy of the spacing of the notches, the design may be carried out in such a way that the time of their engagement with the respective notch may be adjusted in positive and negative direction.

The practical embodiment is shown in Fig. 3, wherein the pawls II and [2 are linked together with two-armed levers I4 and I5, rotatably mounted on a rigid common axis [6 and biased against set screws I! and [8, by the influence of pressure springs l9 and 20. By tightening or releasing a set screw the arms of the auxiliary levers, and the pawls, which are biased into engagement with the notches by means of springs 2| and 22, may be rocked until the desired accuracy of their engagement with the respective notches is obtained.

The two-armed lever I3 is actuated by the second gear train from the gear 6 through the intermediary of suitable transmission means, the desired velocity of which is governed by the braking influence of eddy currents, generated by the rotation of a disc 23 between the poles of a permanent magnet 24. A gear 25 serves to control an emitter of impulses for the drive of a subsidiary clock under the control of the twoarmed lever [3. The said emitter consists of a disc 26 provided with two cams, and rigidly secured to the gear 25, and of a pair of spring blade switches 21, 28. The two-cam disc 23 may be mounted on a common axis with the lever l3.

The correcting initiator co-operates with a control device, consisting of two levers 23, 38, which are provided with intermeshing segments, mounted on the pivots of the respective levers. The two armed lever 29 is controlled by an electromagnet 31 operating against the influence of a spring. 7

For controlling the time indications the device is equipped with a subsidiary clock, provided with a polarized magnet system consisting of permanent magnet I04, and with a rotating armature 32 and an adjustable switch unit, consisting of a gear 33, rigidly secured to the axis of the minute hand and imparting rotation to a pair of earns 34, 35 and an arresting disc 36 by means of a suitable gearing. The cams together with the arresting disc, co-operate with a pair of spring blade switches 31, 38.

The described device operates a wireless receiver 39, the relay 48 of which closes a contact 4| when a tone of expected frequency passes through the output which is tuned by suitable filters. A frequency relay may also be used for this purpose. In such a case the output circuit of the receiver 38 remains normal and an arrangement according to Fig. 4 is used instead of the relay 40. This arrangement consists 01' a tuning fork 42, influenced by an electromagnet 43, the coil of which is connected with the output of the receiver 39 and further of a permanent magnet 44 provided with a suitable coil. If. a current of a frequency corresponding to the resonance of the chosen tuning fork flows through the coil of the electromagnet 43, the fork is .set in vibration and current is induced in a by an abutment pin 52. I the partial ratchet wheel co-operate witha pawl ;53 controlled by a two-arm lever 54, pulled by a lfiiown way in the coil-orthe permanent magnet impulse of the combination. The first controller consists substantially of a ratchet wheel 45 with a pair of toothed portions and with a cam or projection 46 abutting in operative position against a stop 41 under the influence of a spring 48. Its

purpose is to operate the spring blade switches 49. The right hand teeth of the said partial ratchet wheel are adapted to co-operate with a pawl 50 biased into engagement with the teeth bymeans of a spring and journalled on a segment 51, mounted for swinging movement. The

. shape of the pawl 50 is such that in in-operative position of the segment its engagement with the teeth of the ratchet wheel is positively prevented The left hand teeth of spring 55 against the bias of the pawl. This twoarm lever co-operates with an electromagnet 56 whichwhen energized attracts the lever, whereas the release of the lever is electrically delayed for apredeterminedtime interval in a mannerknown per se. The segment mounted for rotation on a common shaft with the partial ratchet wheel 45, is urged clockwise by a spring 51 and its projection 58 co-operates with a spring blade switch 59. Its movement is braked by wings 60 rotated through a stepped up gearing from the toothed circumference of the segment 5!. One member of this gearing is provided with a one-way clutch (not shown), so that the braking influence of thewings 66 is eilective only durin movement of the segment in the direction of pull of the spring 51, whereas itsreturn movement is carried out quickly by a spring 62, operating a lever 6|, if the latter is not attracted by an electromagnet 63.

The other controller consists of a segment 64, mounted for swinging movement and provided with a lug or notch for a pawl, to be described later, and with teeth which impart accelerated movement to braking wings 66, the action of which is controlled by a one-way clutch (not shown) similar to the arrangement of the first controller. Also the lever 61, loaded by a spring 68, operates in a similar way, said lever serving to return or maintain the segment in its initial position against the pulling action of the spring 69, if not influenced by an electromagnet 10.

'The lever 61 co-operates with a rocking cam whereas the other registers their total length with the addition of the length of the individual intervals. The" first controller consists of a swingable segment 16, subjected to the pull or a spring similar to those described above.

I1 and of wings 18 forone-waybrakingeeflect Connected with the segment 16 and insulated. against. it is a smaller segment 19, which may be secured in its adjusted position by a screw 80. Its partial circumference is provided with two insulating inserts 8|, 82 arranged so as to leave .a conductive part between them. A pair of brushes 83, 84 is arranged for co-operation withthe segment. A lever 85, loaded by a spring 86, if not influenced by the electromagnet 88, maintains in, or returns to, its initial position the swinging segment 16, its initial position being fixed by an abutment pin 81. p.

The other controller is similar to the one just described for long impulses or the last impulse of the combination, explained in connection with the analyser for a detailed detection of a time signal.- A difference resides only in the fact that the controller for registering the total or summary reception in the arrangement according to Fig. 2 is adjusted for other time intervals, so that the oscillations of its segment '64 are more efiectively braked. For this reason the wings 66 may be replaced by a more eflicient braking arrangement such as braking by eddy currents or the like. The analyzer forthe reception of a time signal in the form of a summary (totalized) unit, i. e. the arrangement according to Fig. 2, is completed by a relay 89, the armature of which, co-operating with a spring blade contact 9| is quickly'pickedup, when the relay is energized by a current flowing therethrough, whereasits dropping off is electrically delayed for a predetermined. time interval in a manner known per se, The device described operates as follows: The electromagnets of the incorporated subsidiary clock 32, energised in equal, e.; g, one

minute intervals, rotate in a manner knownper se the shaft of the minute hand and the gear 33 rigidly connected therewith. The gear. 33

imparts rotating movement through a suitable gearing to two gears, which are rigidly secured to the cams 34, 35 and. the arresting disc 36.

The ratio of the gearing is such that the cams 34, 35 are rotated through one revolutiononce in an hour, where as the arresting disc 36 carries out one revolution once in 24 hours. The

cam 35 comes therefore to lie with itsoperative notch against a lug of the spring bladecontact 38 every hour similar to the cam .34,-which comes into position against the lug of the spring blade 31. While the lug of the switch 31 swings into the notch of the cam 34 during each of its revolutions, the lug of the switch 38, i retained in its open position by the engagement of the periphery of the arresting disc with 2. lug of the switch and movement of the lug into the cut out portion of the cam 35 to close the switch is permitted only if the notch in the disc 36 is simultaneously positioned against it. By the effect of the chosen ratio thiscoincidence occurs once in 2% hours. Theposition of the cam 34 is adjustable. and its out on portion may be set so that the spring blade switch 31 is operated for instance four minutes later than the contact 38. As both contacts are connected in series, it is clear that after the lapse of the predetermined time the circuit closed by the contact 38 is broken by the contact 31. By the arrangement of a plurality of notches in the disc 36 the switch apparatus of the subsidiary clock may turn on the respective circuit in a plurality of exactly limited'tiine sections while the emission of control signals minals s4, 95 ofalternating current by the mtermediary of spring blade contacts 31, 3B and operated by the described switch arrangement of the subsidiary clock is adapted to energize the relay 40, when a tone having the frequency of the expected signal passes through the output. By closure of the contact 4| the windingof the electromagnet 63 is connected to a positive terminal 92, the other end of its winding being connected directly with the negative terminal of a direct current supply. The contact 4| energizes an electromagnet 55, connected in parallel with the electromagnet 53, the other end of the winding of the electromagnet 56 being connected with a terminal 93 through the contacts offthe spring blade switch 59. The electromagnet U3 attracts the lever .5 so that the released segment 5| is swung under the influence of the spring 51. The pawl 5| freed from the abutting pin 52, swings under the influence of its springinto engagement with a tooth of the partial ratchet wheel 45 entraining the latter in the direction of movement of the segment 5|. The velocity of these movements is determined by the braking effect of the wings t9. Simultaneously with the action of the electromagnet 63, the electromagnet 56 attracts the two-arm lever 54, one .arm of which releases the pawl 53, which under the action of its spring engages the circumference of the partial ratchet wheel 45.

If the receiver 39 receives the expected signal, the duration of closure of the contact 4| is equal to the duration of the first impulse of the signal combination, 1. e. also to the time interval to which the described controller is adjusted. In this case the segment 5| shifts in the manner described above, the partial ratchet wheel through an angle equal to the pitch of the teeth, enlarged by about /3. Its purpose fulfilled, the first impulse of the prescribed combination now ends. The contact 4| breaks the circuit. The lever 6| swings oii under the influence of the spring 62, returning the segment 5| quickly into its initial position. Under the influence of the abutting pin 52, the pawl 50 swings out of engagement with the teeth of the partial ratchet wheel 45, the latter being retained by the pawl 53 in its position, advanced by one tooth. The

circuit of the electromagnet 56 has been disconnected concurrently with that of the electromagnet 63, but its artificially increased "remanence does not permit the lever 54 to swing and so to disengage the pawl 53 before the end of the predetermined interval between the individual impulses of the signal combination. Assuming, that the expected signal is detected, the receiver 39 receives the next impulse before thepawl 53, leaves the teeth of the partial ratchet wheel 45 'under the influence of the two arm lever'54. The relay 40 causes for the second time the contact 4| to close and the described operation is repeated.

At the end of four short combination impulses including the intervals between them, the partial ratchet wheel has been shifted through four teeth and assumed a position in which the lug or projection '46 lies in close proximity of the lug .of the spring blade contact'49. The receiver 39 receives now the last long impulse of i the prescribed combination. The controller initiated by the electromagnets by the repeated closure of the contact is thus broughtinto operation, and the pawl enters the last tooth of the partial ratchet wheel 45. By the first part of its rotation the projection 45 deflects the blade of the spring contact 49 closing thus the latter. Because the last impulse of the combination is a long one and the electromagnet 63 remains operative during its entire duration, the swinging segment 5| continues another moment in its rotating movement until stopped by abutting against the lever Gl, which has been attracted by the electromagnet. Its projection 58 deflects hereby the blade of the spring contact 59, opening the latter and breaking thus the circuit of the electromagnet 55. After the lapse of time during which its artificially increased remanence has been active the lever 54 swings under the influence of the spring 55 and its arm disengages the pawl 53 from the teeth of the partial ratchet wheel 45. The described process occurs in the initial part of the duration of the last impulse of the series. From this moment on the partial ratchet wheel 45 is no more dependent on the pawl 53 and being retained in its position only by the pawl 50 in consequence of the swung out position of the segment 5|, it returns under the influence of its spring 43 into its inoperative position limited by the abutting pin 41, when the last impulse of the prescribed series ends.

The contacts of the spring switch 49, closed in the described way, connect the coil" of the electromagnet 10 with the terminal 93, while the other end of the coil is directly connected with the terminal 92. The electromagnet thus energized attracts the lever 6'! which allows the swingable segment 64 to be rotated by its spring 59. The lever 61 rocks the rocking ca-m H. The pawl 13 released by the latter and biased by a spring abuts against the circumference of the circular part of the segment 64. The velocity of rotation of this segment is determined by the described braking effect of the wings 56. After the lapse of a predetermined time the segment 54 is rotated with its projection 65 against the pawl 13 which, biased by its spring, moves into engagement, releasing thus the blade of the spring switch 14. The closure of its contact connects the coil of the electromagnet 3| to the terminal 92. The other end of the coilof the electromagnet 3| is' connected directly to the terminal 93. In consequence of the adjusted timing of the other controller the electromagnet 3| is energized just before the termination of the last combination impulse.

The segment 54 continues therefore its rotation for another moment, while the electromagnet 3I, under co-operation of the respective parts of the arrangement, carries out the actual control of the master-clock.

The end of the long impulse terminates the entire time-signal. By opening the contact 4|, the relay 40 opens the circuit of the electromagnet 63 and in a manner describedabove returns the segment 5| into its initial position. The contacts of the spring switch 59 are closed again but without any influence on the electromagnet 55, as its circuit is broken by the contact 4|. The

partial ratchet wheel 45, not being retained by spring swings and the rocking cam II swings in opposite direction under the influence of the spring I2. Inrthis'way the pawl 13,.is disengaged and by opening the contacts of the spring switch 14 the circuit of the electromagnet 3| is broken. The segment 64, the projection 65 of which is now .unobstructed, returns quickly into its initial position, limited by the abutting pin 15. The analyzer having fulfilled its operation, is in a position ready to receive a further time signal.

It is clear that if the prescribed length even of a single one of the short impulses is not observed, a regulation of the master-clock does not take place. In this connection it is irrelevant if the'deviation in length occurred for instance, by curtailing the duration of the impulse, as in such a, case the required movement of the partial ratchet wheel 45 does not take place, the pawl 53 does not enter into engagement, so that the ratchet wheel returns into its preceding position. If the prescribed length of any of the impulses is exceeded, the lug 58 breaks the circuit of the electromagnet 56 so that the engagement of the pawl 53 with the teeth of the partial ratchet wheel 45 is discontinued at an undesired moment. The consequence is the same, the ratchet wheel returns into its original position. The same happens also in the case when any of the intervals between the individual impulses exceeds its predetermined time limit. The safety of this arrangement is further enhanced by the other controller which operates under a condition that the last combination impulse has a definite minimum length.

The described device may be replaced by another analyzer shown in Fig. 2 and detecting the control signal by a totalizing method. This device operates as follows:

The relay 89 and the electromagnet 88 are connected in a circuit, controlled by the contact 4| in Fig. 1. They are therefore energized in dependence on the received signal and operate as follows:

When the lever '85 is attracted by the electromagnet 88, it releases the segment 16 for rotation; the relay 89 is also operated and attracts the armature 90, which closes the contacts of the spring switch 9I. The energized electromagnet 10 operates the device described above. The difference resides only in the fact that in the arrangement according to Fig. 2 the adjusted time of swinging movement of the segment 64 equals the total length of the expected time signal with the addition of the length of the intervals between the various impulses whereas the adjusted length in the arrangement according to Fi 1 is equal only to the length of the last combination impulse. I

Assuming that the expected signal is received, an interval occurs after the lapse of time reserved for the first combination impulse. The circuit of the electromagnet 88 is broken, the lever 85, biased by its spring 86, swings and returns the segment 16 to its abutment pin 81 before the segment has reached its operative position. Simultaneously also the circuit of the relay 89 is broken. Its armature 90 remains, however, attracted under the influence of the artificially increased remanence of the relay 89. If the interval does not exceed the predetermined duration of the increased remanence, the second combination impulse arrives before the armature 90 opens the contacts of the spring switch 9| and the continuous movement of the segment 64 is not interfered with. In this way the controller, in fiuenced by the electromagnet I0 summarizes the various impulses and intervals of the prescribed time signal, while in the other controller, which before the termination of the last combination 1 impulse, i. e. in a moment when the segment 64 has swung so far that its lug 65 comes against the pawl I3, which by its engagement closes the contacts of the spring switch 14. ment the circuit of the control electromagnet 3| is completed.

It is clear that also the analyzer, operating on an addition (totalizing) basis reliably prevents any undesired adjusting of the master-clock and necessitates for the adjustment of the clock the reception ofthe prescribed signal which fulfills the predetermined conditions. still the operation of the clock-work tobe described.

The spring member 2, continuously tensioned by the Ferraris motor I, which latter -is connected to a source of alternating current by terminals 94, 95, divides its driving energy by means of gear 5 between the clockwork itself and the apparatus for emitting electric impulses to the subsidiary clocks. The correcting driven by the clockwork, rotates in clockwise direction and co-operates with pawls II, I2 insuch a way that the pawl I I engages thenotches in the disc 9 and the pawl I2 the notches in 1 the disc III. In consequence of the described spacing of these notches the pawls II, I2 carry out their rocking movements in equal, e. g.-

If, for instance, the 1 one minute, intervals. pawl I2 engages a notch in the disc II], the pawl II abuts against the outer circumferenceof the disc 9 and its projecting end servesas an abutment to one of the pins of the two-armedlevers- I I3. 1 During further rotation of the initiator a notch in the disc 9 comes in register with the pawl II. By the engagement of the latter the support of the said pin is removed and the two-armed lever I3, which is driven by thespring member 2 through the gear 6 is rotatedwith a velocity determined by the influence of the braking device, describedabove. After r0}- I tating through its other pin, projecting to the other side, abuts against the extending endof the pawl I2, now out of engagement, so th'atf' the two-armed lever I3 is brought to a stand-f still for such time until the pawl I2 engages T e scribed operation of the machine is-repeated the next notch, i. e. for one minute.

continuously. n I The two-cam disc 2t is rotated by 'means that it carries out half a revolution every minute. During this movement its operates alternatively the pair of spring switches 21, 28 so that within half a revolution it rocks twice in succession the blade of the spring switch 21, leaving the blade of the switch 28 at rest, whereas during the next half rotation the switch 21 is left at rest and the blade of the switch 28 swung In this mo- I There remains initiator,

a gear 25 in dependence on the two arined lever I3, the operation of-which it -follows, s'0

out. The two-cam disc 26 transmits thus to the wire of the subsidiary clocks, connected to the terminals 96, 97, including the subsidiary clock, incorporated in the master-clock device, every minute a special correcting impulse besides the normal driving impulse. This is of particular importance if the subsidiary clock is used together with a device for a continuous synchronisation according to co-pending application Serial No. 648,702 filed February 19, 1946. From the description and wiring diagram as shown it is evident that the current flow of the emitted impulses alternates every minute, the polarity of the correcting impulse corresponding compulsorily to the polarity of the main impulsen The compensation of the time deviations which may occur is carried out by the control mechanism, operated by the energising of the electromagnet 3|, described above, which by attracting one arm of the lever 29 swings out its other arm. Under the influence of the intermeshing segments the lever 30 is simultaneously deflected in opposite direction. The movement of the two levers is similar to the movement of toggles. One of the closed levers engages one of the pins I05, I06 and I07. mounted on the discs 9, I0. If the clockwork is slow, the pin is within the range of the lever 30. As a result of its shifting movement to the central position between the two levers the rotation of the discs 9, I is accelerated by an amount, corresponding to their retardation. In this way the notch is brought against the pawl, which in a given moment arrests the movement of the two-armed lever I3. Th'efpawl' moves into engagement, the lever I3 rotates through half a revolution and an impulse is transmitted to the wire of the subsidiary clocks, which impulse, without the operation of the control device, would have occurred only after the lapse of such time, by which the clockwork with the exact or true time indication was slow. If the clockwork was fast andthe resulting deviation opposite, the pin wouldbe within'the range of the lever 29. In this case the lever 29 returns the pin to the central position between the two levers. The twordiscs 9, I0 are thus rocked against the direction of their rotation, so that the initiation ofanew impulse is delayed by a time equal to the said time deviation. Because the discs 9, I0 are provided with six notches, corresponding to six-minutes of the time scale and with the three compensation pins I05, I06 and I07, the control of the-initiator may take place every other, forjnstance every even minute.

It is clear from the foregoing description, that the control device, operated by the described mechanism, compensates the positive as well as the negative time deviation only by regulating the initiator, entrained by the said sliding clutch, i. e. irrespective of the operation of the clockwork itself. The sliding clutch causes some braking influence at the moment of compensation and can even bring the clockwork to a standstill. The latter could not then be restarted without an outside impulse. It is, therefore, advisable to use amagnetic clutch, operated by'the compensating electromagnets.

An example of such an arrangement is shown.

in Figs. 5 and 6. The releaser, which consists of the two discs 9, I0 with the three pins I05, I06 and I07, as its mechanical actuating device consisting of the pair of levers 29, 30, are replaced by an armature 98 keyed onto shaft 99 and rotatable between the two poles of the electromagnet 3 I. On shaft 99 there is also a friction coupling consisting of two plates IOI, I02 to gether with the relieving member I00. The two platesof this coupling are as usual kept in mutual contact by thespring-pressed relieving member. However, as soon as the electromagnet is excited in order to actuate the armature, then the relieving member I00 is drawn down against the spring pressure by electromagnet 3i and thus releases the plate coupling .evenbeiore the move ment of the armature is carried out. Asa result, the operation of the clock mechanism cannotbe afiected by'the movement of the armature.

What I claim is:

l. A system of clocks including a master clock and 'a' series of subsidiary clocks actuated thereby comprising means for periodic correction by a time signal comprising a combination or impulses transmitted by wireless, wherein a signal of a predetermined frequency is passed over a filter circuit in a receiver as a tone frequency current, and means such as a control device are provided for analyzing the signal received so that only when it consists of the right combination of impulse will the correctionmeans be operated,and wherein said correction means adjusts a releaser of an initiator mechanism for transmitting the actuating impulses from the master to thesubsidiary clocks.

2. Clock system according to claim 1, wherein a central device is inserted in the output circuit of the receiver for the'wireless transmitted impulses and influenced by the individual impulses of the time signal, said control device having two cooperating parts and on correctly receiving the time signal releasing a coupling between the clockwork of the master clock and the releaser, and effecting the time adjustment by means of an adjusting device for the releaser, which also brings about the adjustment as to time 01 a contact device for emitting the current impulses to the subsidiary clocks.

vAcLAv PFE'FFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES, PATENTS Number Name Date 963,192 Webster July 5, 1910 1,747,547 Junghans Feb. 18, 1930' ,869,175 Sprague July 26, 1932 1,997,979 .Smith Apr. '16, 1935 FOREIGN PATENTS Number Country Date 456,050 Great Britain Jan. 28, 1935 

